Plunger for solenoid type relays



1941- J. A. M LEAN, JR 2,253,387

PLUNGER FOR SOLENOID TYPE RELAYS Filed Oct. 15, 1939 WITNESSES: v INVENTOR I (JO/7f? fl/f l ea/gt/r- ATTORN EY 4%? fW/Z W Patented Aug. 19, 1941 PLUNGER FOR SOLENOID TYPE RELAYS John A. McLean, Jr., Springfield, Mass., assignor to Westinghouse Electric & 'Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 13, 1939, Serial No. 299,276

6 Claims.

My invention relates to a magnetically operated switch and is more specifically directed to a specific type plunger for a solenoid operated switch so that the switch will be operated with a snap action due solely to the interaction of the speaccompanying drawing, in which:

Figure l is a schematic showing in cross section of a solenoid type relay having a plunger designed in accordance with the teachings of my invention; and

Fig. 2 is a diagrammatic showing similar to Fig. 1 except that a plurality of stationary contact members are used.

Referring more particularly to Fig. 1, numeral 'I denotes a solenoid preferably of a doughnut shape. Within the solenoid and adapted for a sliding operation there is provided a plunger 2 which comprises two separate pieces of magnetic material, an upper smaller piece 3 and a lower larger piece 4 interconnected by a connector 5, preferably made of brass or other non-magnetic material. It is to be understood, however, that the connector 5, if sufficiently narrow, may also be of magnetic material, such as soft iron, that is, of the same material as pieces 3 and 4. Secured to the lower piece 4 is a rod 6 carrying a pin I which engages a slot 8 in contact carrying lever 9. A contact member In is secured to lever 9, thus acting as a movable contact member which is adapted to engage a stationary contact member II,

The operation of the device is as follows:

When solenoid I is deenergized a spring I2 tends to push lever 9 upwardly about pivot I3 but this upward movement is counterbalanced by the weight of elements 6, 4, 5, and 3, therefore resulting in a balancin of the lever 9 resulting in a positioning of the elements as shown in Fig. 1. In this position of the elements the smaller piece 3 is closer to the center of solenoid I than is the larger piece 4. As current is gradually applied to solenoid I the smaller piece 3 is initially drawn down toward the center of the solenoid inasmuch as it is closer to a central axial point than the lower piece 4. -Hence, piece 3 lines itself with the portion of the magnetic field which is of greatest intensity, that is, within the inner diameter of solenoid I. As the current is increased still further, the increased flux will saturate upper piece 3 and will then flow more and more through the larger mass of magnetic material 4 in the lower part of the plunger, and at a predetermined pickup value of current, the plunger will snap up very rapidly under the action of the magnetic field upon lower piece 4 to assume a position of minimum magnetic reluctance for the circuit, that is, to assume the position in which piece 4 will center itself or line itself symmetrically within the confines of solenoid I so that a maximum number of lines of flux will pass therethrough.

This upward movement of plunger 2 will effect contact engagement between contact members I0 and II. Stationary contact member II may be so positioned with respect to piece 4 that it will contact the movable contact member I0 before piece 4 is in its uppermost position, that is, before it has attained symmetry of position with respect to solenoid I. In this manner the magnetic force of solenoid I which tends to move piece 4 in symmetrical relation therewith will afiord a positive force, holding contact member III continuously pressed against stationary contact member II.

If desired, rod 6 may merely rest on lever 9 instead of being connected thereto exerting a force in ,a downward direction to overcome the tension of spring I2 to open contact members Iill I, and when arm 6 is moved upwardly, it will allow spring I2 to urge contact member Ill into engagement with contact member II.

The device shown in Fig. 2 is similar to that in Fig. 1, and where the same parts are identified the same reference numerals of I to I3 are used. The only difference of Fig. 2 over Fig. 1 is that a pair of additional stationary contacts I4 and I5 are provided. The stationary contact I4 may be for any suitable purpose wherein it is desired to close a circuit while solenoid I is deenergized. Stationary contact I5 which is initially contacted as a result of initial alignment of piece 3 with solenoid I may be for any suitable purpose such as, for example, for completing a circuit to a low voltage source in starting of an electrical motor 9, for instance, a single phase motor as distinguished from stationary contact member II which may complete the circuit through a circuit to the full line voltage. As a matter of fact, stationary contact member may be for closing any suitable circuit requiring completion for a small time period during the building up of the energization of solenoid I.

It is understood that plunger 2 may have a dashpot secured thereto if time limit operation is desired or may exclude such dashpot if no time limit is desired or if pieces 3 and 4 snugly fit within the solenoid carrying frame structure so as to inherently afford time limit operation. It will be understood further that instead of pieces 3 and 4 being of different sizes and of the same material, they may be of the same size but of different materials having different magnetic qualities. Furthermore, while certain contact arrangements have been shown, it will be obvious to those skilled in the art that other contact arrangements may be used wherein the snap action of the plunger in accordance with my invention may be incorporated. Although only two pieces of magnetic material 3 and 4 have been shown it is understood that a greater number of pieces than 2 having different sizes or having different magnetic properties may likewise be used in which event there may be a plurality of switching positions.

I am, of course, aware that others, particularly after having had the benefit of the teachings of my invention may devise other devices embodying my invention, and I, therefore, do not wish to be limited to the specific showings made in the drawin and the descriptive disclosure hereinbefore made, but wish to be limited only by the scope of the appended claims and such prior art as may be pertinent.

I claim as my invention:

1. A magnetically operated switch comprising, in combination, stationary contact means, a ma"- netic coil, an armature, a contact member mounted thereon, said armature having two spaced pieces of magnetic material secured together by a non-magnetic member having a relatively small cross sectional area, means for normally maintaining said pieces on opposite sides of the most central point of said magnetic coil, said spaced pieces being arranged to have their centers of gravity selectively line up with the most concentrated portion of the magnetic field of said coil under the influence of different values of current through said coil, thereby being effective to selectively move with a snap action said contact member carried thereby into two different positions with respect to said stationary contact means for different values of energizing current through said coil.

2. A magnetically operated switch comprising, in combination, stationary contact means, a solenoid, a plunger type armature slidable therein, a contact member mounted thereon, said armature having two spaced pieces of magnetic material secured together by a non-magnetic member having a relatively small cross sectional area, means for normally maintaining said pieces on opposite sides of the most central point of said magnetic coil, said spaced pieces being arranged to have their centers of gravity selectively line up with the most concentrated portion of the magnetic field of said coil under the influence of different values of current through said solenoid thereby being effective to selectively slide with a snap action said contact member carried thereby into two different positions with respect to said stationary contact means for different values of energizing current through said solenoid.

3. A magnetically operated switch comprising, in combination, stationary contact means, a magnetic coil, an armature, a contact member mounted thereon, said armature having two spaced pieces of magnetic material of different values secured together by a non-magnetic member having a relatively small cross sectional area, means for normally maintaining said pieces on opposite sides of the most central point of said magnetic coil said spaced pieces being arranged to have their centers of gravity selectively line up with the most concentrated portion of the magnetic field of said coil under the influence of different values of current through said coil thereby being effective to selectively move with a snap action said contact member carried thereby into two different positions with respect to said stationary contact means for different values of energizing current through said coil and as the result of saturation of the piece having the smaller magnetic value, and means for normally biasing both of said pieces of magnetic material out of alignment with a position corresponding to the most concentrated portion of said magnetic field when said magnetic coil is deenergized.

4. A magnetically operated switch comprising, in combination, stationary contact means, a solenoid, a plunger type armature slidable therein, a contact member mounted thereon, said armature having a plurality of spaced cylindrical pieces of magnetic material of different lengths of the same diameter secured together by a non-magnetic member having a relatively small cross sectional area, means for normally maintaining said pieces on opposite sides of the most central point of said magnetic coil, said spaced pieces being arranged to have their centers of gravity selectively line up with the most concentrated portion of the magnetic field of said coil under the influence of different values of current through said solenoid thereby being effective to selectively slide with a snap action said contact member carried thereby into a plurality of different positions with respect to said stationary contact means for different values of energizing current through said solenoid, and means for biasing all of said pieces of magnetic material out of alignment with the positions corresponding to the most concentrated portion of said magnetic field when said magnetic coil is energized so as to effect progressive alignment of the various pieces in accordance with their sizes in response to different values of current through said solenoid.

5. A magnetically operated switch comprising, in combination, a stationary contact member, a solenoid, an armature having a contact member mounted thereon, said armature having a pair of spaced cylindrical pieces of magnetic material of different lengths but of the same diameter secured together by a non-magnetic member having a relatively small cross sectional area, means for normally biasing said armature in a position in which both of said pieces are out of alignment with an axial central point of said solenoid when said solenoid is deenergized but in which position the smaller piece is closer to such axial central point than the larger piece, said armature being selectively responsive to two predetermined different values of current flow through said solenoid to selectively move either of the centers of gravity of said pieces in alignment with said axial central point of said solenoid, thereby selectively moving the contact member on said armature into either of two predetermined positions with respect to said stationary contact member.

6. A magnetically operated switch comprising, in combination, a pair of stationary contact members, a solenoid, an armature having a contact member mounted thereon, said armature having a pair of spaced cylindrical pieces of magnetic material of different lengths but of the same diameter secured together by a non-magnetic connector, means for normally biasing said armature in a position in which both of said pieces are out of alignment with an axial central point of said solenoid when said solenoid is deenergized but in which position the smaller piece is closer to such axial central point than the larger piece, said armature being selectively responsive to two predetermined different values of current flow through said solenoid to selectively move the axial central point of either of said pieces in alignment with said axial central point of said solenoid, thereby selectively moving the contact member into contact with either of said pairs of stationary contact members in response to difierent values of current flow through said solenoid, a third stationary contact member, and spring means for normally urging the contact member on said armature into engagement with said third stationary contact member when said solenoid ie deenergized.

JOHN A. MCLEAN, JR. 

